The evolution of tape data storage systems is similar to that of many computer components. At first, reel-to-reel systems (somewhat similar to old reel-to-reel audio tape recorders) were used to store data. In 1972, more than a decade before the introduction of the first IBM-PC, the 3M Company introduced the first dual reel quarter-inch tape cartridge designed for data storage. Somewhat more than a decade later, the first single reel tape cartridges and single reel cartridge tape drives were introduced.
Because single reel cartridges are less expensive to produce and require minimal storage space, they are becoming a popular alternative to dual reel cartridges. In fact, single reel cartridge drives are rapidly becoming the preferred design for high-capacity tape-based data storage solutions for data processing systems. Using 600 meters of 12.7 mm-wide tape wound on an reel with a 44 mm hub, a single reel cartridge can store approximately 100 gigabytes of uncompressed data and approximately 200 gigabytes if compressed.
Most single reel cartridges include a housing which encloses a single supply reel onto which a tape is wound. The housing includes an access port through which the tape may be retrieved. A leader pin is generally attached to the free end of the tape. The leader pin may be in the shape of a block, a sphere, a spheroid, a rod or even a T-shaped tab. The supply reel has a central drive hub exposed through a central aperture on one side of the housing. When the cartridge is inserted in a tape drive, a drive spindle engages the drive hub through the aperture in the housing, and a priming mechanism within the drive enters the access port, captures the leader pin, and either directly or indirectly threads the tape over the tape drive's read/write head attaching the tape to a take-up reel located within the tape drive. Data is transferred to and from the tape in a conventional manner.
After the tape has been accessed by the drive, it is rewound onto the supply reel and detached from the take-up reel so that the cartridge may be removed from the drive. Referring to FIG. 1, one or more retention springs 2 are commonly used to secure the leader pin 4 within the access port 6 once the tape is fully rewound onto the supply reel. This process is commonly referred to as a parking operation. Generally, the retention spring 2 is located on one side of the access port 6 while a guide surface 8—commonly formed as part of the cartridge housing—is located on the other. As the tape 9 is being rewound, the leader pin 4 enters the access port riding along the guide surface 8 into a parking slot created by the retention springs 2. The guide surface 8 must be opposite the retention springs 2 to prevent the leader pin 4 from jamming into the retention springs 2 and damaging the cartridge. Avoiding the retention springs 2 during a parking operation narrows the space or “window” through which the leader pin 4 may be received into the access port 6. Enlarging the width of this window, increases reliability of repeated parking operations.
What is needed is an improved retention spring.